The present invention relates to an image reading apparatus and an image reading method in which an image on a stationary original placed on a platen is scanned and read. The present invention also relates to an image reading apparatus and an image reading method for reading an original moving over a platen with an automatic document feeder (ADF). More particularly, the present invention relates to an image reading apparatus and an image reading method that are capable of reading not only a black and white (monotone) original but also a color original.
In recent years, as more personal computers are used to handle color pictures on the internet and electronic photos, there has been an increasing demand for copying, printing and transmitting color images because of superior quality as opposed to black and white images. For that reason, an image reading apparatus has been required to quickly read a color original with high quality.
When an image reading apparatus reads a color original, normally it is necessary to read image data for each of the three primary colors, namely red (R), green (G) and blue (B). Thus, when reading a color original with the same resolution as a black and white original, the image reading apparatus has to read at a slower reading speed than that for a black and white original.
A set of originals to be read in the image reading apparatus may contain both color originals and black and white originals. When the apparatus reads such a set of originals using the color mode, a speed of reading the black and white originals will be dramatically slowed.
To solve this problem, a conventional apparatus pre-scans an original to determine whether the original is in black and white or color. Then, if the original is only in black and white, the image reading apparatus reads at a high speed in the black and white reading mode. Conversely, if the original is in color, it uses the color reading mode with a slower speed. This system is known as ‘pre-scan/actual scan method’.
In Japanese Patent Publication (KOKAI) No. 09-261417, an image processing apparatus is disclosed as a modified version of the ‘pre-scan/actual scan method’ that requires two passes of an original. According to the invention, the reading apparatus is provided with a cycling automatic document feeder. It is determined whether the original is in black and white or color for all documents in advance through a process of transporting the originals through a reading position inside the apparatus. After storing a result of each page of the originals, a stationary reading means reads the originals in black and white at a high speed scanning. Conversely, a moving reading unit scans and reads the originals in color placed stationary on a platen to provide a higher quality.
In Japanese Patent Publication (KOKAI) No. 2001-24850, an image reading apparatus is provided with a color detection device to determine whether an original is in black and white or color. Before reading the original, it is selected to read the original in a color reading mode or in a black and white reading mode. The image reading apparatus reads the original only when a result of the color detection device matches to the reading mode.
However, in the image reading apparatus with ‘pre-scan/actual scan method’ including the one disclosed in Japanese Patent Publication (KOKAI) No. 09-261417, the pre-scan needs to detect whether the original is in monotone or color in advance of the actual scan to read the originals, so it takes longer reading time for the entire originals having both monotone and white documents.
Further, when the apparatus disclosed in Japanese Patent Publication (KOKAI) No. 2001-24850 is set to read in the color mode, monotone originals will not be read if the monotone originals are included in a set of the originals. Therefore, it is necessary to reset the apparatus in the monotone reading mode and read the originals in monotone one more time. Due to the additional time, the reading time for the entire set of originals also takes long.
The first object of the present invention is to provide an image reading apparatus and an image reading method that can read a set of originals containing both color and monotone documents in a shorter period of time. The apparatus has a detection function for color and monotone originals, and reads the monotone documents in a higher speed mode and the color documents in a higher quality mode.
The second object of the present invention is to provide an image reading apparatus and an image reading method that has an ADF and can read a set of originals containing both color and monotone documents in a shorter period of time. The apparatus has a detection function for the color and monotone originals, and reads the monotone documents in a higher speed mode and the color documents in a higher quality mode.
Further objects and advantages of the invention will be apparent from the following description of the invention.